[Disco/Eoan] Revert "selftests/seccomp: Catch garbage on SECCOMP_IOCTL_NOTIF_RECV"

[Thadeu Lima de Souza Cascardo]

BugLink: https://bugs.launchpad.net/bugs/1862588

This reverts upstream commit e4ab5ccc357b978999328fadae164e098c26fa40.

Running linux/tools/testing/selftests/seccomp/seccomp_bpf will fail
with:

seccomp_bpf.c:3149:global.user_notification_basic:Expected -1
(18446744073709551615) == ret (0)
seccomp_bpf.c:3150:global.user_notification_basic:Expected EINVAL (22)
== errno (0)
global.user_notification_basic: Test failed at step #3
[ FAIL ] global.user_notification_basic

The test is checking that the given structure which the kernel will write
to is all zeroes and would return EINVAL otherwise. It's doing it because
it wants userspace to have the possibility in the future to give data there
indicating support for an extension that might be developed in the future.

As the test is there right now, not applying the breaking uABI fix might
cause us to miss applications that would break in future kernels. As the
backport for that is prone for more regression potential, we are deciding
to revert the new test.

Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo at canonical.com>
---
 tools/testing/selftests/seccomp/seccomp_bpf.c | 13 +------------
 1 file changed, 1 insertion(+), 12 deletions(-)

diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c b/tools/testing/selftests/seccomp/seccomp_bpf.c
index a819ab57fafe..f80b248eb389 100644
--- a/tools/testing/selftests/seccomp/seccomp_bpf.c
+++ b/tools/testing/selftests/seccomp/seccomp_bpf.c
@@ -3154,18 +3154,7 @@ TEST(user_notification_basic)
 	EXPECT_GT(poll(&pollfd, 1, -1), 0);
 	EXPECT_EQ(pollfd.revents, POLLIN);
 
-	/* Test that we can't pass garbage to the kernel. */
-	memset(&req, 0, sizeof(req));
-	req.pid = -1;
-	errno = 0;
-	ret = ioctl(listener, SECCOMP_IOCTL_NOTIF_RECV, &req);
-	EXPECT_EQ(-1, ret);
-	EXPECT_EQ(EINVAL, errno);
-
-	if (ret) {
-		req.pid = 0;
-		EXPECT_EQ(ioctl(listener, SECCOMP_IOCTL_NOTIF_RECV, &req), 0);
-	}
+	EXPECT_EQ(ioctl(listener, SECCOMP_IOCTL_NOTIF_RECV, &req), 0);
 
 	pollfd.fd = listener;
 	pollfd.events = POLLIN | POLLOUT;
-- 
2.20.1